Ever since the Internet became a mass social phenomenon in the 1990s, people have worried about its effects on their privacy. From time to time, a major scandal has erupted, focusing attention on those anxieties; last year’s revelations concerning the U.S. National Security Agency’s surveillance of electronic communications are only the most recent example. In most cases, the subsequent debate has been about who should be able to collect and store personal data and how they should be able to go about it. When people hear or read about the issue, they tend to worry about who has access to information about their health, their finances, their relationships, and their political activities.

But those fears and the public conversations that articulate them have not kept up with the technological reality. Today, the widespread and perpetual collection and storage of personal data have become practically inevitable. Every day, people knowingly provide enormous amounts of data to a wide array of organizations, including government agencies, Internet service providers, telecommunications companies, and financial firms. Such organizations -- and many other kinds, as well -- also obtain massive quantities of data through “passive” collection, when people provide data in the act of doing something else: for example, by simply moving from one place to another while carrying a GPS-enabled cell phone. Indeed, there is hardly any part of one’s life that does not emit some sort of “data exhaust” as a byproduct. And it has become virtually impossible for someone to know exactly how much of his data is out there or where it is stored. Meanwhile, ever more powerful processors and servers have made it possible to analyze all this data and to generate new insights and inferences about individual preferences and behavior.

This is the reality of the era of “big data,” which has rendered obsolete the current approach to protecting individual privacy and civil liberties. Today’s laws and regulations focus largely on controlling the collection and retention of personal data, an approach that is becoming impractical for individuals, while also potentially cutting off future uses of data that could benefit society. The time has come for a new approach: shifting the focus from limiting the collection and retention of data to controlling data at the most important point -- the moment when it is used.

ON THIS TOPIC

Two years ago, the physicist Neil Gershenfeld argued that the next great digital revolution would come not in computing or communication but in fabrication. Today, 3-D printing, which uses digital data to rapidly construct physical objects, is more accessible than ever. Automakers are placing ...

In 2010, U.S. President Barack Obama articulated his vision for the future of American space exploration, which included an eventual manned mission to Mars. Such an endeavor would surely cost hundreds of billions of dollars -- maybe even $1 trillion. Whatever the amount, it would be an ...

These days, most of Washington seems to believe that a major cyberattack on U.S. critical infrastructure is inevitable. In March, James Clapper, U.S. director of national intelligence, ranked cyberattacks as the greatest short-term threat to U.S. national security. General Keith Alexander, the ...